formatting the drive will not erase the drive, in order to do that I use the free version of "kill disk" I keep a copy on a floppy, boot from floppy, run program, it physically over writes the entire hard drive, then reinstall your operating system and other software, this should insure a clean install
if you just reformat the hard drive and reinstall windows will look for and reuse sections of data on the drive that may contain malicious script allowing the problem to remain (I have had it happen)
